1. Field of the Invention
This invention relates to a sheet material feeding apparatus in which a plurality of sheets are supplied one by one to a sheet receiving station at regular or irregular intervals, and then the sheets are brought to a sheet sending station where they are stacked to be ready for dispatch one after another.
2. Description of the Prior Art
There has been hitherto known a radiation image read-out apparatus such as an X-ray image read-out apparatus, in which a stimulable phosphor sheet bearing an X-ray image or picture of a human body or any other object is subjected to the sweeping of a laser beam and is stimulated by the laser beam to emit light according to the recorded radiation image and the emitted light is detected by a photodetector thereby obtaining an image signal which represents the X-ray image or picture. A laser beam modulated with the image signal is projected onto a photosensitive film recording medium to make a record of the X-ray image or picture. Stimulable phosphor sheets capable of storing X-ray pictures are usually used and the phoshpor sheets each bearing an X-ray picture thereon are brought to a sheet-feeding station of the X-ray image read-out apparatus manually or by a conveyor means, and the phosphor sheets are automatically brought to a recording station one after another. In most cases, X-ray photographs are not taken at regular intervals, and this is particularly true in the case of medical diagnosis. Because of this, no direct conveyor means is provided between the X-ray image pick-up apparatus and the associated X-ray image read-out apparatus. Instead, the phosphor sheets are intermittently supplied one by one and are temporarily stored and stacked in the sheet receiving station of the X-ray image read-out apparatus. Then, the stack of sheets at the sheet receiving station is brought to the sheet sending station for delivery one by one to the recording station of the X-ray image read-out apparatus. The so-constructed sheet conveyor system of the X-ray image recording apparatus permits the X-ray image read-out apparatus to operate independently of the timing and rate at which the phosphor sheets are supplied from the X-ray image pick-up apparatus, thus increasing the efficiency of operation. Because of the independent operation of the X-ray image read-out apparatus, there arises no need to interrupt the taking of X-ray pictures even if the X-ray image read-out apparatus should break down or malfunction, or if phosphor sheets should be supplied from the X-ray image pick-up apparatus at a rate beyond the working capability of the X-ray image read-out apparatus.
In one conventional sheet feeding apparatus of this type in which sheets are brought from a sheet receiving-and-storing station to a sheet-by-sheet sending station, a number of sheets are stacked on each other, and these sheets are later picked up one by one beginning from the lowermost to be sent to the subsequent station. In another conventional sheet feeding apparatus, sheets are sequentially put in individual compartments and the sheet inlet and sheet outlet of each of the compartments are opened and closed by, for instance, a link mechanism in a way appropriate for storing and delivering the sheets one after another, thus causing the sheets to sequentially fall in and out of the compartments under their own weight. In the former conventional apparatus which picks up the sheets one by one beginning from the lowermost, it is difficult to assure the separation of a single sheet without bringing along the overlying sheet in the stack of sheets. Another problem is that when the sheet is drawn from the bottom of the stack, it is apt to be scratched by rubbing against the sheet above and the supporting surface below. This is a serious problem in an X-ray image read-out apparatus in which the sheets being handled are phosphor sheets. Also, in the latter conventional apparatus the overall size of the apparatus increases with the amount of the sheet material to be handled, and the structure of the apparatus becomes complicated. Also disadvantageously, if a sheet is bent at any part, it is apt to catch as it falls through the inner space of the compartment. Another problem common to these conventional sheet feeding apparatuses is that it is difficult to handle sheet materials of different sizes when they are mixed irregularly.